1 /* NETMAP - static NAT mapping of IP network addresses (1:1).
2 * The mapping can be applied to source (POSTROUTING),
3 * destination (PREROUTING), or both (with separate rules).
6 /* (C) 2000-2001 Svenning Soerensen <svenning@post5.tele.dk>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
13 #include <linux/config.h>
15 #include <linux/module.h>
16 #include <linux/netdevice.h>
17 #include <linux/netfilter.h>
18 #include <linux/netfilter_ipv4.h>
19 #include <linux/netfilter_ipv4/ip_nat_rule.h>
21 #define MODULENAME "NETMAP"
22 MODULE_LICENSE("GPL");
23 MODULE_AUTHOR("Svenning Soerensen <svenning@post5.tele.dk>");
24 MODULE_DESCRIPTION("iptables 1:1 NAT mapping of IP networks target");
29 #define DEBUGP(format, args...)
33 check(const char *tablename
,
35 const struct xt_target
*target
,
37 unsigned int targinfosize
,
38 unsigned int hook_mask
)
40 const struct ip_nat_multi_range_compat
*mr
= targinfo
;
42 if (!(mr
->range
[0].flags
& IP_NAT_RANGE_MAP_IPS
)) {
43 DEBUGP(MODULENAME
":check: bad MAP_IPS.\n");
46 if (mr
->rangesize
!= 1) {
47 DEBUGP(MODULENAME
":check: bad rangesize %u.\n", mr
->rangesize
);
54 target(struct sk_buff
**pskb
,
55 const struct net_device
*in
,
56 const struct net_device
*out
,
58 const struct xt_target
*target
,
62 struct ip_conntrack
*ct
;
63 enum ip_conntrack_info ctinfo
;
64 u_int32_t new_ip
, netmask
;
65 const struct ip_nat_multi_range_compat
*mr
= targinfo
;
66 struct ip_nat_range newrange
;
68 IP_NF_ASSERT(hooknum
== NF_IP_PRE_ROUTING
69 || hooknum
== NF_IP_POST_ROUTING
70 || hooknum
== NF_IP_LOCAL_OUT
);
71 ct
= ip_conntrack_get(*pskb
, &ctinfo
);
73 netmask
= ~(mr
->range
[0].min_ip
^ mr
->range
[0].max_ip
);
75 if (hooknum
== NF_IP_PRE_ROUTING
|| hooknum
== NF_IP_LOCAL_OUT
)
76 new_ip
= (*pskb
)->nh
.iph
->daddr
& ~netmask
;
78 new_ip
= (*pskb
)->nh
.iph
->saddr
& ~netmask
;
79 new_ip
|= mr
->range
[0].min_ip
& netmask
;
81 newrange
= ((struct ip_nat_range
)
82 { mr
->range
[0].flags
| IP_NAT_RANGE_MAP_IPS
,
84 mr
->range
[0].min
, mr
->range
[0].max
});
86 /* Hand modified range to generic setup. */
87 return ip_nat_setup_info(ct
, &newrange
, hooknum
);
90 static struct ipt_target target_module
= {
93 .targetsize
= sizeof(struct ip_nat_multi_range_compat
),
95 .hooks
= (1 << NF_IP_PRE_ROUTING
) | (1 << NF_IP_POST_ROUTING
) |
96 (1 << NF_IP_LOCAL_OUT
),
101 static int __init
ipt_netmap_init(void)
103 return ipt_register_target(&target_module
);
106 static void __exit
ipt_netmap_fini(void)
108 ipt_unregister_target(&target_module
);
111 module_init(ipt_netmap_init
);
112 module_exit(ipt_netmap_fini
);